The Dementia Study in Northern Norway is an open controled intervention trial carried out in nine rural municipalities, five of which allocated to intervention and four to control. A RCT with donepezil and placebo is superimposed on all patients included in the study. In this way the study has a 2x2 factorial design. The outcome measures are changes in cognitive performance and ADL function measured by standardized cognitive and neuropsychological tests every four months during a one-year follow-up.